The present invention relates to implantable cochlea stimulating electrodes for improving the hearing of the hearing impaired and, more particularly, to an improved cochlea stimulating electrode assembly, insertion tool, holder and method of implantation.
U.S. Pat. No. 4,400,590 issued Aug. 23, 1983 for "Apparatus For Multichannel Cochlear Implant Hearing Aid System" describes and illustrates a multichannel intra-cochlear electrode for electrically stimulating predetermined locations of the auditory nerve within the cochlea of the ear. The electrode comprises a plurality of exposed electrode pairs spaced along and imbedded in a resilient curved base for implantation in accordance with the method of surgical implantation described in U.S. Pat. No. 3,751,605 issued Aug. 7, 1973 for "Method Of Inducing Hearing". By that method, bone above the round window of the cochlea is surgically exposed and removed to permit free access to the round window. The tip of the curved base of the electrode is inserted through the round window and into the cochlea. By simultaneously gently gripping sides of the base and pushing axially thereon the balance of the electrode base is eased through the round window into the lower scala of the cochlea to follow along the basilar membrane. The electrode pairs are very fragile and are often subject to damage during such implantation. Also, the implantation procedure is known to be very difficult to perform, requiring utmost skill on the part of the surgeon. In fact few surgeons have been able to master the implantation technique.
The present invention provides an improved cochlea stimulating electrode assembly and insertion tool which eliminates the simultaneous gripping and pushing of the electrode during implantation, greatly reduces the difficulty of the procedure and thereby provides an improved method of electrode implantation which is free of electrode damage. The electrode assembly design also permits the surgeon to easily attach the lead of the assembly to a patient's skull at the cochlea entrance during implant of the assembly.